This invention relates to a door hinge with improved security characteristics for preventing entry by burglars, vandals, trespassers and the like.
As used in doors which open outwardly, conventional hinges possess the fault that surreptitious entry may be gained by removing the hinge pins and pulling the door outwardly from its frame. In the past there have been various proposals for preventing such forced entry, such as by securing the hinge pin with a locking pin inaccessable when the door is closed, thus preventing removal of the hinge pin; for example, see U.S. Pat. No. 3,621,512.
Various arrangements have also been proposed to prevent opening of a door when the hinge pin has been removed or the hinge knuckles sawed through, and the door is closed and locked. Such devices have consisted of structures which interact when the leaves of the hinge are in their overlapping, i.e., closed position, so as to prevent relative parallel movement. An example is shown in U.S. Pat. No. 30,970 to Johnson which employs a stud attached to one leaf for entering an opening in the opposite leaf when the hinge is closed.
The aforementioned hinges possess the disadvantage of being ineffective against an intruder who possesses a hacksaw blade or the like. In the case where the hinge pin is made tamper resistant, the entire knuckle-hinge pin assembly may be sawed off and the door thereby removed. Also, where a stud-aperture interlock is employed, the door may be removed by removing the hinge pins or sawing off the knuckles or barrel, and then sawing through the stud.